Study on time range of definite integral in derivation process of chloride ion diffusion theoretical model of concrete

Abstract

In the study of the durability of concrete structures, the chloride ion diffusion coefficient (Dt) is a key parameter that directly affects the prediction of concrete's service life. This study aims to explore the relationship between the chloride ion diffusion coefficient in concrete and the "curing age (tref)" and "exposure time (t)." By conducting long-term curing and seawater exposure experiments on three different mixes of high-performance concrete samples, we collected experimental data with a curing age of 3 years and a seawater exposure time of 4.5 years. Through in-depth analysis of these data, we found that there is a significant power function relationship between the chloride ion diffusion coefficient and exposure time, while the relationship with curing age is not significant. This finding suggests that in the derivation of the concrete chloride ion diffusion theory model, the time range of the definite integral of Dt should be from 0 to t, rather than from tref to tref+t. Furthermore, we have validated the concrete life prediction model using actual data from the Swedish Marine Exposure Station, further confirming the accuracy and reliability of our research results. This study provides a more scientific and accurate theoretical basis for the durability assessment and service life prediction of concrete structures.